Telephone system.



O. M. LEIGH.

TELEPHONE SYSTEM.

APPLICATION FILED DEO.10, 1908.

954,445. Patented Apr. 12, 1910.

0. M.DLEIGH.

TELEPHONE, SYSTEM.

APPLICATION FILED 13110.1(),1908,

954,445, Patented Apr. 12, 1910.

2 SHEETS-SHEET 2.

UNITD STATES PATENT OFFICE.

OSCAR M. LEIGH, OF GENOA, ILLINOIS, ASSIGNOR 'IO CRACRAFT-LEICH ELECTRIC COMPANY, OF GENOA, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEllI.

earn-r5.

Specification of Letters Patent.

Application filed December 10, 1908.

Patented Apr. 12, 1910.

Serial No. 466,778.

To all whom it may concern:

Be it known that I, OsoAP. M. Lniorr, a citizen of the United States, residing at Genoa, in the county of Dekalb and State of Illinois, have invented a certain new and useful Improvement in Telephone Systems, of which the following is a full, clear, con cise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone systems, and is more particularly applicable to systems of this nature where they are used 'in the operation of trains and where it is essential to provide through telephone serv- I ice and block telephone service of noninterfering nature in the operation of railroads.

More particularly, my invention is an improvement of my system disclosed in my patent application filed June 19th, 1908, Serial No. 439,312.

Generally speaking, my invention contemplates a metallic circuit over which a plurality of telephones can converse metallically, and at the same time contemplate the provision of additional circuits arranged in tandem over said circuit, which tandem circuits are end to end and are noninterfering.

It is the prime object of my invention to provide a greatly simplified system of this character, which eliminates the necessity of use of a large number of repeating coils otherwise necessary, and provides necessary ringing facilities in accordance with this invention, which make it commercially operative.

I will describe my invention more in detail by reference to the accompanying drawing, illustrating one embodiment thereof, in WhlCh- Figure 1 shows diagrammatically a system as constructed in accordance with my invention, and Figs. 2 and 3 are details of the telephone substation sets as used in my system.

Referring to the drawings, I have shown a pair of line wires 1 and 2, which connect together various stations (I, Z), 0, (Z, c, f, and h. spatchers set. At the various stations there are provided terminals 3 and 4, to which a telephone set is to be connected, which telephone set is shown in detail in Fig. 2, and which telephone set is metallically arranged so that all of these sets in pa 'allel can con- Station It, I prefer as the train deverse with the train-despatche1"s set at the station It.

In the drawing in Fig. 1 I have not shown this despatching set, but have for the sake of clearness shown it in a separate view in Fig. 2. The train-despatche1"s set consists of the transmitter 44, battery 45, induction coil 4&6, receiver 47, listening key and ringing key 6. The listening key connects the train-despatche1"s set at station it in bridge of the conductors 1 and 2. The ringing key is adapted to send high frequency impulses metallieally over the line wires 1 and 2 through the agency of the battery 7, and interrupter 8, springs 9 and 10 being provided to close the circuit, through the battery 7, whenever it is desired to send such high frequency signaling current.

The high frequency signaling current is adapted to operate a high frequency relay 11, which high frequency relay has a disk armature 12, having a weighted contact arm 13, which normally rests against the diaphragm. hen high frequency impulses are sent through the relay 11, it attracts the armature, and the arm 1.3 cannot follow with a su'llicient rapidity, so that the circuit is opened and thereby permits the armature 14 l of an auxiliary relay 15 to be retracted by the spring 16, thus closing a circuit through a battery 17 and a local-bell 18. An impedance coil 19 is shown, in series with the relay 11, to prevent the undue deflection of voice current therethrough.

The substation despatching set consists of the receiver 20, switchhook .21., transmitter 22, induction coil 23, and battery 24. It will thus be seen that the traindespatchers set at station It and the various substation despatchers sets, as shown in Fig. 2, one of which substation sets is connected to each of the terminals 3 and 4. along the line wires 1 and 2 are arranged for metallic telephonic intercommunication.

It will be noted, of course, that the traindespatchers telephone i7 is usually at the train-(lespatchers car, so that no calling devices are necessary for the substation sets at the stations a, b, 0, (Z, c, f and g.

In accordance with my invention, it is desired to augment this metallic service by service between the various stations (I, b, c, d, c, f and 5 each of which said stations represents the terminal of a bloek----the railstation 6.

road block, for instance, extending between the stations (4, 7), or between any two other stations. It is desired that communication be permitted between the various blocks, which communication shall be noninterfering, and which shall not injuriously influence the metallic intercommunication between the despatching sets. For this purpose, I interpose at regular intervals in the line wires 1 and 2, and in this instance at the stations 0 and c, repeating coils 25, which repeating coils transmit from one section of the line to the adjoining section all metallic impulses, but which repeating coils are so arranged that if a circuit is taken off of either one of the windings comprising said repeating coil at its center thereof and connected to ground, the currents in one winding are not transmitted to the other winding. Thus for instance at station the windings 26 will transmit metallic impulses to the windings 27, but any impulses in the windings 26, due to a circuit 28, will not be transmitted to the windings 27, or viceversa.

Thus it will be seen that additional cir cuits can be operated over the two line wires 1 and 2 in parallel and the ground return, which will not interfere with adjoining stations. For instance, station 0 can selectively communicate, through the circuit comprising conductor 28, with station 6, or upon actuation of the reversing switch 43 with Stations a and 0 might listen in, but as the operators with whom they might wish to converse; namely, 1) and (Z, are in those instances busy, extra noninterfering circuits between these stations are unnecessary. Similarly station 6 can communicate with stations f and 9, but it will not affect stations (1 and (Z.

In order to avoid the necessity of repeating coils at each one of these substations, to carry out this scheme I have devised a new and novel arrangement, by means of which I can use impedance coils, which are much cheaper and impose less serious conditions on the circuit, at some of the stations, and yet get the results which I could obtain were repeating coils to be used at all of the stations. To this end I include impedance coils 30 in bridge of the lines 1 and 2 at stations at, 6, (Z, 7" and g. I then take off circuits at the middle points of these impedance coils through conductors 31, which circuits are adapted for connection to telephone sets, and adapted for communication over the two line wires 1 and 2 in parallel and the ground return. These conductors 31, through instrumentalities which will be explained in detail, connect with terminals 32 and 33, and similarly the conductors 28 terminate in terminals 32 and 33, which terminals 32 and 33 are adapted for connection to a telephone set shown in detail in Fig. 3, which is the block telephone set, and which consists of a receiver 3 1-, adjustable impedance coil 35, transmitter 36, switchhook 37, induction coils 38, and battery 39; likewise a pulsating current, positive and negative generator 40, and a reversing-switch 41, which reversing-switch serves either to connect positive or negative pulsating current to the terminals 32,

Thus the telephone sets shown in Fig. 3 are connected to each one of the stations at, I), 0, (Z, c, and g, and the general scheme of operation is as follows: Station a can communicate with station I), and station 0, but cannot go beyond station 0. Station 0 can communicate with stations (Z and 6, but cannot go beyond; likewise stations 6, f, and y can communicate, and they will not disturb stations 0 and (Z. It will be seen from this that it is not possible to carry on two conversations in opposite direction from station (Z, but this is not necessary, as there is only one operator at a station in any event,

and he can either communicate with station c or station 6. It will be seen that of course two conversations could be carried on from station 6 to stations (Z and 7, but as there is one operator only at station 6, only one conversation will be carried on, although the repeating coil is here included to disturb the continuity of the block'telephone service. It will thus be apparent that repeating coils and impedance coils alternate, except at the end stations a and 9, where it is not necessary to break the continuity of the ground block service.

From what has been described heretofore as to the apparatus of the block telephone as shown in Fig. 3, it is seen that said block telephone is provided with apparatus so that it can furnish positive and negative calling current. It is essential to call the stations on either side of the block station selectively, and for this purpose I employ pulsating current ringers, which have the polarity, positive and negative, as shown upon the drawing, Fig. 1, from which it will be apparent, for instance, that station 0 can call station Z) without disturbing station a, or can call station (Z without disturbing station 6; likewise, station (Z can call station 0 without disturbing station a, or vice-versa. This, as before stated, is accomplished through the arrangement of the polarized ringers 12.

It will be noted that when station to calls station Z), it will not disturb station 0.

From all of the foregoing, it will appear that two different kinds of telephone service can be carried on over the line wires 1 and 2; namely, the metallic service over the despatchin-g set, and noninterfering tandem circuits can operate over the block telephone sets. Likewise, selective calling is provided between the block sets as described.

Various modifications, of course, can be made without departing from the spirit of the invention herein disclosed, and 1 do not wish to limit myself to the precise arrangement shown, but

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent is:

1. A telephone system comprising a metallic circuit, repeating coils interposed at intervals for breaking the metallic continuity of said circuit, telephone sets adapted for connection to and metallic conversation over said circuit, a second group of telephone sets, impedance windings interposed between each telephone set of the second group and said circuit to permit conversation between the telephone sets of said second group over the wires of said circuit in parallel and a return circuit, and selective signaling devices whereby the telephone sets of the second group can signal each other selectively, the impedance windings aforesaid preventing interference between simultaneous conversations of the telephone sets of the first group and the telephone sets of the second group.

2. A telephone system comprising a metallic circuit, repeating coils interposed at intervals for breaking the metallic continuity of said circuit, telephone sets adapted for connection to and metallic conversation over said circuit, a second group of telephone sets, impedance windings interposed between each telephone set of the second group and said circuit to permit conversation between the telephone sets of said second group over the wires of said circuit in parallel and a return circuit, and selective signaling devices comprising polarized ringers whereby the telephone sets of the second group can signal each other selectively, the impedance windings aforesaid preventing interference between simultaneous conversations of the telephone sets of the first group and the telephone sets of the second group.

3. A telephone system comprising a metallic circuit, repeating coils interposed at intervals for breaking the metallic continuity of said circuit, telephone sets adapted for connection to and metallic conversation over said circuit, electro-magnetic call signals for said sets, a second group of telephone sets, impedance windings interposed between each telephone set of the second group and said circuit to permit conversation between the telephone sets of said second group over the wires of said circuit in parallel and a return circuit, and selective signaling devices whereby the telephone sets of the second group can signal each other solectively, the impedance windings aforesaid preventing interference between simultaneous conversations of the telephone sets of the first group and the telephone sets of the second group.

4t. A telephone system comprising a metallic circuit, repeating coils interposed at intervals for breaking the metallic continuity of said circuit, telephone sets adapted for connection to and metallic conversation over said circuit, a second group of telephone sets, impedance windings interposed between each telephone set of the second group and said circuit to permit conversation between the telephone sets of said second group over the wires of said circuit in parallel and a return circuit, and selective signaling devices comprising polarized ringers and selective current generating devices, whereby the telephone sets of the second group can signal each other selectively, the impedance windings aforesaid preventing interference between simultaneous conversations of the telephone sets of the first group and the telephone sets of the second group.

5. A telephone system comprising a metallic circuit, repeating coils interposed at intervals in said circuit to maintain telephonic continuity throughout said circuit and breaking the metallic continuity thereof, telephone sets adapted for connection to said circuit for metallic conversation there-over, impedance coils bridged across said circuit intermediate of said repeating coils, and a second group of telephone sets adapted for connection between said repeating and impedance coils and a return circuit, so that simultaneous conversations respectively between the telephone sets of each group will not interfere with each other.

6. A telephone system comprising a metallic circuit, repeating coils for maintaining the telephonic continuity of said metallic circuit, telephonic appliances arranged for bridge connection with said circuit adapted for intercommunication, telephone appliances provided for a plurality of additional noninterit'ering telephone circuits over said metallic circuit and a return circuit, each of said additional circuits terminating at its extremities in one of the i'vindings of a repeating coil, impedance coils bridged across said metallic circuit intermediate of said repeating coils, and telephonic appliances connected centrally to said impedance coils and said return circuit, whereby each telephonic appliance connected to an impedance coil aforesaid is adapted for (.Olnl'l'llllllCtltlOH through the additional telephonic circuit aforesaid respectively which terminates in the repeating coils intermediate of which said impedance coil is arranged.

7. A telephonic system comprising a metallic circuit, repeating coils for maintaining the telephonic continuity of said metallic circuit, telephonic appliances arranged for bridge connection with said circuit adapted for intercommunication, telephone appliances provided for a plurality of additional noninterfering telephone circuits over said metallic circuit and a return circuit, each of said additional circuits terminating at its extremities in one of the windings of a repeating coil, impedance coils bridged across said metallic circuit intermediate of said repeating coils, telephonic appliances connected centrally to said impedance coils and said return circuit, whereby each telephonic appliance connected to an impedance coil aforesaid is adapted for communication through the additional tele phonic circuit aforesaid respectively which terminates in the repeating coils intermediate of Which said impedance coil is arranged, and signaling means Whereby the telephonic appliances upon each of the additional circuits aforesaid can signal between themselves.

In Witness whereof, I hereunto subscribe my name this 13th day of November A. D., 1908.

OSOAR'M. LEIGH.

Witnesses ALEX. C. REID, E. B. CAMPBELL. 

